I’ll try to be very succinct in the argument I’d like for folks to address:

All we have to go on to believe he is a progressive is his word. We have not seen him act on those words in a smaller political context, to see that he not only talks the talk but walks the walk, like we for instance could with Mamdani, Tlaib, Sanders, Cortez, etc. Other than his word, which we had for Fetterman, Sinema, Obama, etc as well, what makes you believe this man actually believes what he says, and isn’t just paying lip service to get into the senate.

It was there in the comment I replied to as well, but maybe this rephrasing helps you out.